Actually I was going more along the lines of an ADF. I had read a page many, many moons ago about the Navy’s development of navigation systems. This was a pretty interesting account. Anyway a friend and I were talking about old navigation stuff and……well you know how it goes when two history geeks start in…..never found that page again.

However, thanks for the second link! I had stumbled across that one a year or so ago and couldn’t remember where to find it.